The present invention relates to a virtualization technique of a switch base in the SAN (Storage Area Network) and to a technique which controls the quality of services at the time of making an access to a virtual storage.
In the SAN which connects a plurality of computers (or servers) and a plurality of storage systems through a network, there is a technique which virtualizes and utilizes the data storage areas of the storage systems. The virtualization is a technique which causes the plural storage systems connected with the SAN to appear one or more storage systems for the servers. The virtualization of the storage systems is the optimum method for the case, in which the plural storage systems are to be stepwise summarized. In the future, the cost for a manager can be reduced by reducing the storage systems to be managed.
Hereinafter, the virtualized data storage area provided for the servers by the storage systems will be called the “virtual volume”, and the data storage area provided by the actual storage systems will be called the “real volume”.
The virtualization of the data storage area is performed between the servers and the storage systems. The virtualization of the data storage area is performed: by a method (a first method) using a volume management software in the servers in which server applications are executed; a method (a second method) using a computer which is provided just upstream of the storage system with a plurality of interfaces to connect the storage systems; and a method (a third method) using a network device configuring the SAN. (For example, referred to as: “Understanding of ‘Network’ and ‘Virtualization’” edited by Ryota Tamaki; p. 49 to 51 of Nikkei IT Professional, September, 2002; and p. 13 to 15 of “Realization of Function Intensification and Batch Management by Virtualization of Storage” of Nikkei Windows Pro, August (No. 65), 2002).